Detecting with reasonable precision the fertile period of the female reproductive cycle would have significant benefits from a human "family planning" aspect as well as with animal husbandry. For example, by detecting the fertile period, a woman would be able to determine when intercourse would likely lead to conception. Such information could therefore be used by the woman to either refrain from or engage in intercourse if contraception or conception is desired, respectively. Similarly, livestock breeders would be able to maximize successful inseminations with knowledge of the ovulation cycle of the particular breeding animal.
It is well known that a number of physiological changes ensue during a woman's menstrual cycle and various tests have been developed as an aid to family planning. For example, it is known that the water content of vaginal mucus varies during the menstrual cycle. In this regard, U.S. Pat. No. 4,019,820 to Kopito et al (the entire content of which is incorporated expressly hereinto by reference) discloses an in vitro device which detects ovulation during a menstrual cycle using the transmissivity and/or diffusivity properties of vaginal mucus. That is, according to Kopito et al '820, a vaginal mucus sample must first be positioned between a pair of plates at a specific pressure and temperature in order to provide a mucus stratum of predetermined thickness. A photometer then measures the optical transmissivity and/or diffusivity in order to determine the phase of the menstrual cycle.
The techniques disclosed by Kopito et al '820 are not without problems. Specifically, since the apparatus is quite cumbersome and the mucus sample must be positioned with great care and accuracy with respect to the photometer, it is impractical for "home" use, but instead must be administered by clinical technicians. Furthermore, since the device is only capable of detecting vaginal mucus properties in vitro, there is a real risk that the water content in the mucus will change in the short time it takes to obtain a sample and to prepare it for testing in the Kopito et al '820 apparatus, thereby potentially leading to inaccurate readings.
What has been needed in this art, therefore, is a relatively simply device that can be employed in vivo to detect the ovulation period of females. It is towards fulfilling such a need that the present invention is directed.
Broadly, the present invention relates to a device that detects in vivo physiological changes in a female's cervical mucus. These changes correlate with the timing of ovulation and thus provide a marker for the fertile period of the menstrual cycle. The fertile period is the time interval during which unprotected intercourse can lead to pregnancy. The period extends several days before the day of ovulation and ends immediately after that day. More particularly, the device of the present invention measures the water content, or hydration of cervical mucus, which has been shown to increase several days before ovulation. These changes in mucus hydration correlate with the pre-ovulation rise in luteinizing hormone (LH) which only precedes ovulation by 24-36 hours, and thus occurs after the onset of the fertile period. Other hormone changes, e.g., those of estradiol or progesterone, are less consistent within and among women than the increase in mucus hydration and thus are less robust markers of the fertile period. The device of this invention therefore measures in vivo the mucus hydration by its direct correlate, the index of refraction of the mucus. As a result, problems associated with in vitro measurement of mucus hydration (e.g., possible mucus dehydration when a sample is removed from the body) are eliminated.
The device of this invention generally includes a refractive index detector having a light source, a photoreceptor and a light guide positioned so as to guide light from the light source to the photoreceptor. The light guide includes at least one active surface to be wetted by the cervical mucus. The detector may be planar or curvelinear and may be embedded within a distal sensing head or extend upright therefrom (e.g., so as to somewhat penetrate the external cervical os during use). Most preferably, the light guide is fabricated from a fluorocarbon polymer.
Most preferably, the device of this invention will include a proximal handle which allows the user to manipulate the distal sensing head into close proximity to the external cervical os. The handle may include a source of electrical power (e.g., a DC battery pack, solar cell or the like), a processor for processing the signal received from the photodetector indicative of the cervical mucus refractive index, and a human-readable display (e.g., an alpha-numeric display, light indicator, analog display or the like). A relatively slender (as compared to the handle) stem operatively connects the handle to the distal sensing head. The sensing head may be formed as a one-piece structure with the stem and angled relative thereto so as to assist in placement of the detector in close proximity to the external cervical os. Alternatively, the sensing head may be connected to the stem to allow for relative pivotal articulation to permit selective adjustment of the sensing head's angular orientation relative to the stem. The stem itself may be entirely rigid, or may be flexible.
Further aspects and advantages of this invention will become more clear after careful consideration is given to the detailed description of the preferred exemplary embodiments thereof which follow.